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1# RUN: llc -o - %s -mtriple=x86_64-- -run-pass=machine-cp | FileCheck %s2 3# When MachineCopyPropagation eliminates a dead 'copy', its associated debug4# information becomes invalid. as the recorded register has been removed.5# It causes the debugger to display wrong variable value.6#7# When in the debugger, on the line "return read1;", the value of "read1"8# is reported as '4', where it should be '1'.9#10# MIR generated with:11# clang -S -g -O2 -emit-llvm pr38773.cpp -o pr38773.ll -mllvm12# llc pr38773.ll -stop-after=tailduplication -simplify-mir 13#14# // pr38773.cpp15# int main() {16# volatile int foo = 4;17# int read1 = foo;18# int read2 = foo;19#20# switch ((read1 == 4) ? 3 : 1) {21# case 1:22# read1 *= read2;23# break;24# case 3:25# read1 /= read2;26# break;27# }28# 29# return read1;30# }31#32# Update the register for the '@llvm.dbg.value' associated with 'read1', when33# the 'copy' is removed, to be the 'source' register.34 35--- |36 ; ModuleID = 'pr38773.ll'37 source_filename = "pr38773.cpp"38 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"39 target triple = "x86_64-pc-linux-gnu"40 41 define dso_local i32 @main() local_unnamed_addr !dbg !7 {42 entry:43 %foo = alloca i32, align 444 store volatile i32 4, ptr %foo, align 445 %foo.0.foo.0. = load volatile i32, ptr %foo, align 446 %foo.0.foo.0.6 = load volatile i32, ptr %foo, align 447 %cmp = icmp eq i32 %foo.0.foo.0., 448 br i1 %cmp, label %sw.bb1, label %sw.bb49 50 sw.bb: ; preds = %entry51 %mul = mul nsw i32 %foo.0.foo.0.6, %foo.0.foo.0.52 br label %sw.epilog53 54 sw.bb1: ; preds = %entry55 %div = sdiv i32 4, %foo.0.foo.0.656 call void @llvm.dbg.value(metadata i32 %div, metadata !12, metadata !DIExpression()), !dbg !1357 br label %sw.epilog58 59 sw.epilog: ; preds = %sw.bb1, %sw.bb60 %read1.0 = phi i32 [ %div, %sw.bb1 ], [ %mul, %sw.bb ]61 call void @llvm.dbg.value(metadata i32 %read1.0, metadata !12, metadata !DIExpression()), !dbg !1362 ret i32 %read1.063 }64 65 declare void @llvm.dbg.value(metadata, metadata, metadata) #066 67 !llvm.dbg.cu = !{!0}68 !llvm.module.flags = !{!3, !4, !5}69 !llvm.ident = !{!6}70 71 !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 8.0.0 (trunk 343183)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)72 !1 = !DIFile(filename: "pr38773.cpp", directory: ".")73 !2 = !{}74 !3 = !{i32 2, !"Dwarf Version", i32 4}75 !4 = !{i32 2, !"Debug Info Version", i32 3}76 !5 = !{i32 1, !"wchar_size", i32 4}77 !6 = !{!"clang version 8.0.0 (trunk 343183)"}78 !7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !11)79 !8 = !DISubroutineType(types: !9)80 !9 = !{!10}81 !10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)82 !11 = !{!12}83 !12 = !DILocalVariable(name: "read1", scope: !7, file: !1, line: 3, type: !10)84 !13 = !DILocation(line: 3, column: 7, scope: !7)85 86...87---88name: main89 90body: |91 92 bb.2.sw.bb1:93 liveins: $ecx94 95 $eax = MOV32ri 496 $edx = MOV32r0 implicit-def dead $eflags97 IDIV32r killed renamable $ecx, implicit-def $eax, implicit-def dead $edx, implicit-def dead $eflags, implicit $eax, implicit killed $edx98 renamable $ecx = COPY $eax99 ; CHECK: IDIV32r killed renamable $ecx100 ; CHECK-NEXT: DBG_VALUE $eax, $noreg, !12, !DIExpression(), debug-location !13101 DBG_VALUE $ecx, $noreg, !12, !DIExpression(), debug-location !13102 ; The following mov and DBG_VALUE have been inserted after the PR was103 ; resolved to check that MCP will update debug users that are not104 ; immediately after the dead copy.105 ; CHECK-NEXT: $edx = MOV32r0106 $edx = MOV32r0 implicit-def dead $eflags107 ; CHECK-NEXT: DBG_VALUE $eax, $noreg, !12, !DIExpression(), debug-location !13108 DBG_VALUE $ecx, $noreg, !12, !DIExpression(), debug-location !13109 $eax = COPY killed renamable $ecx110 RET 0, $eax111 112...113